Conventional heat-sensitive mimeograph stencils typically comprise a film for heat-sensitive mimeograph stencil and a porous support adhered to the film with an adhesive. Conventional films for heat-sensitive mimeograph stencils include vinyl chloride-vinylidene chloride copolymer film, polypropylene film and polyethyleneterephthalate film, and conventional porous supports include tissue paper and polyester gauze.
However, if the film for heat-sensitive mimeograph stencil is made of a vinyl chloride film, vinylidene chloride copolymer film or a polypropylene film as disclosed in, for example, Japanese Patent Disclosure (Kokai) No. 48395/85, the film does not have sufficient stiffness and its slipperiness is bad, so that a thick film has to be used. Further, since the energy of crystal fusion .DELTA.Hu of the resin is great, the heat-sensitivity is low. As a result, characters and paint-printed symbols or figures (symbols or figures such as and in which ink is applied in a large area) cannot be printed clearly. On the other hand, if the film for heat-sensitive mimeograph stencil is made of a polyethyleneterephthalate film as disclosed in, for example, Japanese Patent Disclosure (Kokai) Nos. 85996/85 and 16786/84, the film has sufficient stiffness and the slipperiness is relatively good. However, since its .DELTA.Hu is great, to promote heat-sensitivity the thickness of the film must be made considerably small. As a result, the film tends to be broken easily and to be wrinkled during the film forming process, so that the production yield may be largely reduced. In either case, the shades of the printed characters, and the thicknesses of the printed characters are uneven, and the thin black characters cannot be printed due to the low sensitivity.